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Glucose enzyme electrode using cytochrome b(562) as an electron mediator
Junko Okuda1, Junko Wakai, Noriko Yuhashi
1Department of Biotechnology, Faculty of Technology, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei, 184-8588, Tokyo, Japan.
Biosensors & Bioelectronics
|April 23, 2003
Summary
New glucose sensors utilize natural electron acceptors like cytochrome b(562) with enzymes pyrroloquinoline quinone glucose dehydrogenase (PQQGDH) and glucose oxidase (GOD). This eliminates the need for synthetic mediators in electrochemical biosensors.
Area of Science:
- Biotechnology and Biosensor Development
- Electrochemistry and Enzyme Engineering
Background:
- Direct electrochemical recycling of prosthetic groups in enzymes like pyrroloquinoline quinone glucose dehydrogenase (PQQGDH) and glucose oxidase (GOD) is often limited on electrode surfaces.
- Synthetic electron mediators are commonly used in electrochemical biosensors but can introduce complexity and potential toxicity.
- Cytochrome b(562) (cyt b(562)) is a naturally occurring electron acceptor with potential applications in biosensor technology.
Purpose of the Study:
- To construct and evaluate glucose sensors employing PQQGDH and GOD without synthetic electron mediators.
- To investigate the efficacy of using Escherichia coli soluble cytochrome b(562) (cyt b(562)) as a natural electron acceptor for these enzymes.
- To demonstrate the potential of cyt b(562) in direct electron transfer biosensor systems.
Main Methods:
- Co-immobilization of PQQGDH or GOD with a 100-fold molar excess of cyt b(562) onto electrode surfaces.
- Electrochemical investigation of the enzyme/cyt b(562) modified electrodes in the presence of glucose.
- Comparison of sensor performance (detection limit, linearity) with electrodes lacking cyt b(562).
Main Results:
- Both PQQGDH/cyt b(562) and GOD/cyt b(562) electrodes exhibited significant current responses to glucose.
- Electrodes with enzyme alone showed no current increase, highlighting the role of cyt b(562).
- The PQQGDH/cyt b(562) sensor had a detection limit of 0.1 mM and linearity up to 2 mM, while the GOD/cyt b(562) sensor showed a 0.8 mM detection limit and linearity up to 9 mM.
Conclusions:
- A functional glucose sensor system can be successfully constructed using a natural electron acceptor (cyt b(562)) instead of synthetic mediators.
- Cyt b(562) effectively facilitates direct electron transfer for PQQGDH and GOD, enabling glucose detection.
- This approach demonstrates the viability of cyt b(562) in direct electron transfer biosensors for oxidoreductases lacking intrinsic electron transfer subunits.